The present invention relates to direct current motors, and more particularly to D.C. regulator controlled motors having an exciter winding connected to the armature and commutating pole windings of the motor by means of diodes.
Published German Patent Application No. 1,563,981 discloses a motor control arrangement wherein a D.C. motor is energized by way of an electronic D.C. regulator. In this arrangement, the exciter winding is connected with the armature and commutating pole windings by means of diodes. This arrangement allows control to be exercised over the entire speed range of the D.C. motor as well as provide for field suppression by a single D.C. regulator. However, this arrangement has a disadvantage in that the commutating system of the motor is subjected to stresses by voltage peaks across the armature windings, which are short-circuited by the commutating brushes. These voltage peaks are induced in transformer-like fashion by rapid changes in the field current or magnetic field flux.